Folded cascode amplifier circuit

Abstract

A folded cascode amplifier circuit includes: an input stage having a pair of transistors and configured to output a positive phase intermediate signal and an opposite phase intermediate signal; a cascode amplification stage having pairs of transistors connected in multiple stages, to which the positive phase intermediate signal and the opposite phase intermediate signal are supplied, and which is configured to output a positive phase output signal and an opposite phase output signal, which are differential signals; a first capacitor connected between a signal line of the positive phase intermediate signal and a signal line of the opposite phase output signal; and a second capacitor connected between a signal line of the opposite phase intermediate signal and a signal line of the positive phase output signal.

What is claimed is: 
     
       1. A folded cascode amplifier circuit comprising:
 an input stage having a pair of transistors and configured to output a positive phase intermediate signal and an opposite phase intermediate signal, which are differential signals; 
 a cascode amplification stage having pairs of transistors connected in multiple stages, to which the positive phase intermediate signal and the opposite phase intermediate signal are supplied, and which is configured to output a positive phase output signal and an opposite phase output signal, which are differential signals; 
 a first capacitor connected between a signal line of the positive phase intermediate signal and a signal line of the opposite phase output signal; and 
 a second capacitor connected between a signal line of the opposite phase intermediate signal and a signal line of the positive phase output signal. 
 
     
     
       2. The folded cascode amplifier circuit according to  claim 1 , further comprising:
 a first resistor element connected between the first capacitor and the signal line of the positive phase intermediate signal or between the first capacitor and the signal line of the opposite phase output signal; and 
 a second resistor element connected between the second capacitor and the signal line of the opposite phase intermediate signal or between the second capacitor and the signal line of the positive phase output signal. 
 
     
     
       3. The folded cascode amplifier circuit according to  claim 1 , wherein
 the pair of transistors of the input stage has PMOS transistors. 
 
     
     
       4. The folded cascode amplifier circuit according to  claim 2 , wherein
 the pair of transistors of the input stage has PMOS transistors. 
 
     
     
       5. The folded cascode amplifier circuit according to  claim 1 , wherein
 the pair of transistors of the input stage has NMOS transistors. 
 
     
     
       6. The folded cascode amplifier circuit according to  claim 2 , wherein
 the pair of transistors of the input stage has NMOS transistors.